This invention relates to footwear, and particularly to athletic footwear.
In copending application Ser. No. 510,671, is disclosed footwear incorporating a special propulsion plate extending from the medial portion of the heel through the arch to a position forwardly of the metatarsal heads. This construction has been found highly effective in cooperating with the spring energy of the natural biomechanism of the foot, storing energy and then releasing the energy in response to flexure during each step. This specially configurated plate is formed of layers of oriented fibers, normally carbon (graphite) fiber, embedded in polymer and enclosed between the midsole and the outsole.
The midsole for athletic shoes is typically formed of a foam polymer such as expanded EVA ethylene vinyl acetate polymer (EVA).
In U.S. Pat. 4,934,072, entitled FLUID DYNAMIC SHOE, is set forth a special pad inserted in the heel region of the midsole.